In lifting crane service, a 2-BLOCK condition defined as physical contact of a hook block with a boom point or associated boom point apparatus may occur. Heretofore, equipment used in lifting crane service such as mobile cranes either relied entirely on operator skill for safety and did not have a 2-BLOCK condition warning system or had a 2-BLOCK condition warning system which would indicate an imminent 2-BLOCK condition and prevent it from occurring. Operators have heretofore sometimes found it necessary to intentionally cause a 2-BLOCK condition to prevent the hook block from swaying when the mobile crane is in transit. Furthermore, during lifting crane service, operators have occasionally found it necessary or desirable to obtain the absolute maximum lifting height available from the crane, thus necessitating operation close to or actually in a 2-BLOCK condition.
In prior art systems having a 2-BLOCK condition warning or prevention feature, a manual override feature was sometimes provided to enable intentional operation in a 2-BLOCK condition. Such a manual override feature further required manual resetting from the OVERRIDE state when operation in a 2-BLOCK condition was terminated. Such a system is disadvantageous because it relies on the operator to take affirmative action to restore the system to its monitoring state.